More and more banks keep asking for your entire crypto transaction history when you want to convert it to fiat currency.
This is to make sure that all taxes are paid, and that the person who converts crypto to fiat did not get it from criminal activities.

Let's say that Frank (USA) bought bitcoin in 2015, swapped for altoins a few times, made profits but never declared those to the IRS.
Now when Frank wants to withdraw his crypto funds and spend the money, he is worried about receiving a huge tax bill or even facing criminal charges (tax evasion). He chooses not to cash out.

So Frank travels around the world and is now dating Sonya from the Philippines.
Frank donates his bitcoin to Sonya by sending it to her BTC address.

Sonya now goes to her bank in the Philippines and wants to convert her BTC, received as a donation, to fiat currency that she can spend with Frank.

The bank is asking for a transaction history, but she does not have one because it was a donation.

What happens then?

In the future, I think it's gonna get much more difficult for banks to trace where exactly the BTC came from.
For most people it just sat there in a hardware wallet and the link to the original purchase is not hard to demonstrate.
But that will change over time, especially when BTC is regularly exchanged between people in different jurisdictions.